Rotatable seesaw base



March 1953 G. wozNAcK 2,633,316

' ROTATABLE SEESAW BASE Filed Dec. 2, 1948 INVENTOR. 660/?66 WOZ/YA c/(.

Patented Mar. 31, 1953 UNITED STATES PATENT OFFICE 1 Claim.

This invention relates to see-saws, and more particularly to a see-saw construction which is adapted to rotary as well as reciprocal rocking movements.

It is the object of the present invention to provide a see-saw construction wherein the fulcrum is rotatable through an arc of 360 degrees. It is the object of this invention to provide a see-saw which includes a supporting base or standard, and an upright fulcrum which is rotatively journalled and supported thereon, the pivotal portion of the see-saw including a support which is centrally pivoted upon said fulcrum to permit rotation thereof throughout the pivotal movements of said see-saw.

It is the further object of this invention to provide a novel support forming a part of the see-saw and which carries seats at its opposite outer ends, said support being of a parallelogram construction.

It is the further object of this invention to provide a pivotal support for a see-saw of parallelogram construction including a pair of spaced horizontally extending elements which are centrally pivoted to said fulcrum and a pair of vertically extending end elements pivotally joined to the respective ends of said horizontal elements, with seats being carried by said end elements.

t is the still further object of this invention to provide a pivotal support upon said fulcrum with the horizontal elements pivotally mounted thereon so that said end elements will be maintained at all times in substantially upright positions to assure that the seats will remain substantially horizontal at all times.

- It is the still further object of the present invention to so construct the support mounting that the pivotal support of one of said horizontally extending elements is out of line with the corresponding pivotal connections of its opposite ends with the corresponding ends of the aforementioned end elements whereby the pivotal support as a whole is slightly biased or under tension when pivoted from a horizontal position.

It is the still further object of this invention to provide a novel mounting for the see-saw fulcrum upon which the support is pivotally positioned which included upright guide bushings carried by the see-saw base as well as a lower thrust bearing for supporting said fulcrum with a minimum of friction.

These and other objects will be seen from the following specification and claim in conjunction with the appended drawing in which:

Fig. 1 is a side elevational view of the see-saw.

Fig. 2 a similar view partially broken away showing the see-saw support pivotally inclined from the position shown .in Fig. L

Fig. 3 is a top plan view of Fi 1.

Fig. 4 is an .elevational section on line 4-4 of Fig. 1.

Fig. 5- is a plan section on line 55 of Fig. l. Fig. 6 is a plan section on line 66 of Fig. 1.

Fig. '7 is an elevational section on line 1-1 of Fig. 1.

Fig. 8 is a plan section on line .8-8 of Fig. 1; and

Fig. 9 is a fragmentary enlarged elevational view illustrating the thrust bearing.

It will be understood that the above drawing illustrates merely the preferred embodiment of the invention, and that other embodiments are contemplated within the scope of the claims hereafter set out.

Referring to the drawing, the see-saw consists of the base which includes the intersecting horizontally arranged elements in and I 2 arranged at right angles to each other, said elements being suitably notched at their central points for interlocking engagement.

Upwardly inclined supporting elements l3 are secured at M at their lower ends adjacent the outer ends of the base element I I. A corresponding pair of upwardly inclined supporting elements I5 are secured at [6 at their lower ends adjacent the outer ends of the intersecting base element I2.

Consequently there are four upwardly inclined reenforcing members i. e. elements l3 and 15 whose inner ends approach each other and are joined to an upright fulcrum support generally indicated at IT.

Said support i! consists of the four upright right angle members l8, whose opposite outer surfaces are arranged in parallel spaced relation to one of the corresponding surfaces of an adjacent angle member. Consequently, the upper ends of the inclined elements 43 respectively project between the corresponding pairs of spaced angle members 18, being secured therebetween by the bolts l9.

Similarly the other pair of inclined supporting elements i5 project at their upper ends between corresponding pairs of spaced surfaces of said angle members as illustrated in Fig. 8, being secured with respect thereto by the bolts 20.

The bolts l9 and 20 thus effectively secure the inclined elements l3 and I5 as well as the four spaced right angle supports with respect to each other in the manner illustrated in Figures 1 and 8.

Referring to Figure 8 which is a plan section taken on line 8-8 of Figure 1 bearing blocks 2| preferably constructed of wood, are positioned between the upper ends of the angle members l8 and are secured with respect thereto by the bolts or rivts 22.

The inner surface 23 of each of said blocks is concave with the outer edges of said concave surfaces coinciding with the respective apex of each of said angle members l8, to thereby provide a circular guide bearing for the see-saw fulcrum for operation in the manner hereafter set out.

As shown in Figures 4 and 9 the upper vertical edges of the reinforcing elements l3 and I are similarly concaved to define at points 23 a, circular opening providing a second guide bearing for the lower end of the fulcrum support for operation in the manner hereafter described. f As shown in Figures 4, 5 and 9 a rectangular block 24 is interposed between corresponding opposite walls of the angle members 18 and is secured in a horizontal position therebetween by the bolts 25 as illustrated in Figure 5.

A thrust bearing 26 is snugly positioned within angle elements I8 mounted upon the block 24,

being slightly concave to receive and operatively support with a minimum of friction the ball 21 or otherwise convex arcuate element carried at the lower end of the fulcrum hereafter described.

The aforementioned fulcrum includes the upright parallel spaced supports 28 which are joined together by the bolts 29. Preferably hollow shaft 33 projects partially up into and between the lower ends of the supports 28 and is secured with respect thereto by the bolts 3|.

Shaft 30 forming a part of said fulcrum is positioned within the angle members l8 being guidably journalled through top bearing blocks 2| and within the lower bearing surfaces 23 which form a part of the reinforcing elements [3 and IS.

The lower end of shaft 33 is convex as at 2? or has a ball shaped member secured thereon for cooperative engagement with the top surface of the slightly concave thrust bearing 26. It is contemplated that the radius of the surface of the thrust bearing will be greater than the radius of the convex element 2'! to minimize the frictional relationship therebetween.

The rockable support which carries seats at its opposite ends is pivotally mounted upon the fulcrum 23-33 and consists of a parallelogram construction which includes as shown in Figure 1, a pair of parallel spaced horizontally extending elements 32 and 33 which at their central portions extend between the upright supports 28 being pivotally joined thereto by means of the transverse bolts 29 above described and as illus .trated in Figure 4.

The upright parallel spaced end elements 34 are arranged at opposite ends of elements 32 and 33 being pivotally joined thereto by the transverse shafts 35 and the transverse bolts 36. Thus, the end portions of end elements 34 are respec' tively pivotally joined to the corresponding opposite ends of elements 32 and 33 to form a parallelogram construction;

As shown in Figures 3 and 7 there are a pair of upright parallel spaced end elements 34 at each end of the horizontal elements 32 and 33 to thereby cooperatively and retainingly receive said ends in the manner illustrated in Figure 7.

Oppositely extending horizontally arranged seat supports 31 project between the lower ends of the spaced upright end elements 34 and are suitably secured thereto as by the screws or other suitable means 38.

The seats 39 are centrally positioned upon supports 31 and are respectively secured thereon in the position shown by means of the right angle brackets 40.

In view of the pivotal mountings 29 for the horizontal elements 32 and 33 it is seen that the end elements 34 remain in a substantially upright vertical position regardless of the amount that element 32 and 33 are tilted, as indicated in Figure 2. It is to be concluded that the seats 39 will consequently be at all times in a substantially horizontal position being efiectively secured to end elements 34.

The see-saw hereinabove described thus has a rotatable fulcrum 23-30 which is supported upon the fulcrum support generally indicated at I1, and at the same time said fulcrum contains and supports the pivotal support 32-33 for the seats 39 so that said toy provides for rotation of the riders throughout their pivotal up and down see-saw movements.

As shown in Figure 7 the shafts not only provide suitable connecting means between horizontal element 32 and the upper ends of elements 34 but have secured thereon the oppositely arranged handle grips 4|.

Central semi-circular or arcuate disc 42 is secured to the underside of element 32 being positioned between the supports 28 and serve to prevent pinching of ones fingers between element 32 and the supports 23.

Similarly a pair of convex discs 43 are carried centrally upon the top and bottom edges of the element 33 adjacent its pivot 29 to serve the same purpose of preventing a users finger from being pinched between element 33 and the elements 28.

Similar safety features are incorporated in the end elements 34 and include the top circular surfaces 44 formed in the end elements 34 as well as the lower circularly formed surfaces 45 therein. Said surfaces 44 and 45 have substantially constant radii respectively about the pivotal points 35 and 35 and are also intended to prevent pinching of the users fingers between element 34 and the corresponding ends of the elements 32 and 33.

As shown in Figure 5 the diameter of the shaft 32 is such as to permit slight engagement of the outer surface of said shaft with the corresponding apexes of the upright angle elements l8, to act as guides for the rotatable shaft. Said guide lines corresponding to the inner apex of said angle elements coincide with the arcuate surfaces 23 of the bearing blocks 2|.

Similarly said inner apex lines correspond to the arcuate bearing surfaces 23 at the upper ends of the reinforcing elements 13 and I5 to minimize the wear thereof.

By the present parallelogram construction 32, 33 and 34 it is seen that the seats 39 will be maintained substantially horizontal at all times. In order that this pivotal see-saw support be not freely movable, one of the pivotal supports 29 such as the lower thereof as shown in Figures 1 and 2, is arranged slightly out of line with the corresponding pivotal connections 36 at the ends of element 33. This has the effect of biasing the pivotal support placing the same under a slight tension, particularly placing a slight bending moment upon the ends of the upper element 32 when the parallelogram construction is pivoted to any inclined position such as that shown in Figure 2.

It will be seen that placing the pivotal point 29 of element 33 out of line with pivotal points 36 will have the effect of making the distance 3629 slightly greater than the distance 35-29 and as a result any pivotal movement of the parallelogram construction from the position shown in Figure 1 will cause a slight bending vertically of the ends of element 32 about its pivotal support 29. It will be seen in examining Figure 2 that the element 32 is slightly bowed thus placing the entire parallelogram construction under tension.

Consequently, the pivotal element of the seesaw construction is not free floating but on the other hand will always remain in the angular position that it is left in when the riders are off.

This biasing of this parallelogram construction normally prevents the end elements 34 from dropping down so as to engage its surface upon which the base I l-l 2 rests.

Circular ring 46 has a central opening to loosely receive the shaft 30, said ring being adapted to rest upon the upper ends of the right angle members I8. When assembled ring 46 is normally in spaced relation to the lower ends of the supports 28, and is adapted as a safety fea- Having described my invention, reference upright intersecting slots, a pair of upwardly 40 converging reinforcing elements joined to said base with their upper ends positioned between a corresponding pair of angle irons and secured thereto, a second pair of upwardly converging elements spaced from and arranged at right angles to said first pair, joined to said base with their upper ends positioned between a second corresponding pair of angle irons and secured thereto, a horizontal block within one of said slots and secured to said angle irons, a concave thrust bearing upon said block arranged centrally of said apexes, and the upper ends of said reinforcing elements being arcuately formed as upright bearing surfaces, and blocks secured to said angle irons Within said slots at their upper ends, the inner surfaces thereof being arcuately formed as bearing surfaces, said apexes registering with the interior cylindrical surfaces formed by said bearing surfaces for cooperation therewith and for minimizing the wear thereof.

GEORGE WOZNACK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 879,937 Woodward Feb. 25, 1908 1,398,166 Winchel Nov. 22, 1921 1,417,816 Foote May 30, 1922 1,553,418 Watts Sept. 15, 1925 1,694,785 Lange Dec. 11, 1928 1,709,446 Travers Apr. 16, 1929 1,810,817 Brainard et al June 16, 1931 2,033,523 Husted et a1 Mar. 10, 1936 FOREIGN PATENTS Number Country Date 205,458 Switzerland Sept. 16, 1939 

